UV radiation blocking protective layers compatible with thick film pastes

ABSTRACT

This invention relates to novel compositions comprising a protective polymer layer and a UV blocking agent. This is used in the fabrication of electronic devices using thick film pastes. The present invention is also an electronic device fabrication process using the compositions. The protective polymer layer is fabricated from materials, which are insoluble after irradiation in the ester-type solvents contained in the thick film paste. By appropriate selection of protective film polymers, the protective film can be compatible with the thick film paste and can be further used to shield portions of the thick film paste from UV irradiation.

FIELD OF THE INVENTION

The present invention relates to a composition and a process using aspecial protective layer for the fabrication of electronic devices thatuse thick film pastes.

TECHNICAL BACKGROUND

The present invention relates to a composition and a process forconstructing electronic devices wherein a substrate is coated with aconducting layer that is further coated with a thick film paste. Thethick film paste may contain materials such as glass frit, variousconductors, photo-imageable polymers and, usually a solvent. In thefabrication of these devices, photo-definable protective layers may beused to isolate photoimageable thick film deposits from other elementsof these electronic devices such as conductive layers. A problem arisesin some of these devices in that the solvent used in the thick filmpastes, usually an ester or ether type solvent, is frequently aggressiveto the polymer protective layer and may lead to short circuits. This canlead to problems on the surface of the substrate such as pealing ordissolution of the protective layer from the substrate when that layeris exposed to the thick film paste. An additional utility of suchprotective layers is the blocking of UV radiation so that the amount ofradiation from the backside of the device reaching the thick film isreduced, thus increasing contrast between irradiated regions and regionsprotected by the protective layer in a self-aligned fabricationenvironment.

-   -   Wang et al in the Proceedings of the SPIE—The International        Society for Optical Engineering (1999) vol. 3906, p. 619-24        describes the electrical characterization of polymer thick film        resistors.    -   Fukuda et al (U.S. Pat. No. 5,601,638) describes a thick film        paste for use in the formation of circuit components.    -   Ezaki (U.S. Pat. No. 5,362,927) reports a thick film hybrid        circuit board device formed by lamination.    -   Kazunori et al (JP 2001155626 A) provide a method for producing        a display substrate.    -   Takehiro and Shigeo (JP 10340666 A) describe a field emission        element.    -   Kazunori and Shinsuke ((JP 2001111217 A) provide a method of        forming laminated wiring.

SUMMARY OF THE INVENTION

The present invention is composition of a material which can befabricated to a photodefinable protective layer comprising a UV blockingagent selected from the group consisting of: nitro benzoic acid, methoxybenzoic acid, nitro naphthalic acid, methoxy naphthalic acid, 3,5dimethoxy,4-hydroxy cinnamic acid, cinnamic acid and their otherderivatives, 2 hydroxyl aryl benzotriazole and its derivatives, 2hydroxy benzophenone and its derivatives, and anthracene sulfonic acidand its derivatives and a polymer in which at least 50 mole percent ofthe monomers in the polymer comprise a structure selected from the groupconsisting of:

where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ ishydrogen or a lower alkyl where the definition of lower alkyl includesalkyl groups having 1 to 6 linear or cyclic carbon atoms;

where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ andR₄ are independently hydrogen or a lower alkyl where the definition oflower alkyl includes alkyl groups having 1 to 6 carbon atoms and thejoining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂ and either R₃ orR₄ to form a 5-, 6-, or 7-membered ring; and

where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ andR₄ are independently hydrogen or a lower alkyl where the definition oflower alkyl includes alkyl groups having 1 to 6 carbon atoms and thejoining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂ and either R₃ orR₄ to form a 5-, 6-, or 7-membered ring.

Suitable polymers for the above process are polymers selected from thegroup consisting of 1-ethoxyethyl methacrylate, 1-ethoxyethyl acrylate,1-butoxyethyl methacrylate, 1-butoxyethyl acrylate, 1-ethoxy-1-propylmethacrylate, 1-ethoxy-1-propyl acrylate, tetrahydropyranylmethacrylate, tetrahydropyranyl acrylate, tetrahydropyranylp-vinylbenzoate, 1-ethoxy-1-propyl p-vinylbenzoate,4-(2-tetrahydropyranyloxy) benzyl methacrylate,4-(2-tetrahydropyranyloxy) benzyl acrylate, 4-(1-butoxyethoxy) benzylmethacrylate, 4-(1-butoxyethoxy) benzyl acrylate t-butyl methacrylate,t-butyl acrylate, neopentyl methacrylate, neopentyl acrylate,1-Bicyclo{2,2,2}octyl methacrylate (or acrylate) and their derivatives,1-Bicyclo{2,2,1}heptyl methacrylate (or acrylate) and their derivatives,1-Bicyclo{2,1,1}hexyl methacrylate (or acrylate) and their derivatives,1-Bicyclo{1,1,1}pentyl methacrylate (or acrylate) and their derivativesand 1-adamantyl methacrylate (or acrylate) and their derivatives.

Suitable UV blocking agents for the above process include compoundsabsorbing UV light in the range of 320 to 400 nm, commonly known as UV-Aradiation, that have good solubility in the above mentioned polymers,and is easily removed by aqueous developer. Examples of the blockingagents include aromatic acids which absorbs g-line and I-line radiation.The examples of such acid are nitro benzoic acid, methoxy benzoic acid,nitro naphthalic acid, methoxy naphthalic acid, anthracene sulfonicacid, anthraquinon sulfonic acid, cinnamic acid, and 3,5 dimethoxy4-hydroxy cinnamic acid. Another class of UV blocking agents arecompounds which undergoes an excited state intramolecular protontransfer, and they can be exemplified with aromatic ketone andbenzotriazole derivatives.

The present invention is further a process comprising coating anelectronic device structure with a positive photo-imageable protectivelayer comprising a UV blocking agent and a polymer in which at least 50mole percent of the monomers in the polymer comprise a structureselected from the group of materials cited above.

The present invention also includes an electronic device fabricated bythe above process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows self-alignment with an UV blocking protective film.

DETAILED DESCRIPTION

A self-aligned environment in device fabrication means that one of morelayers of the device blocks radiation such that those layers function asa built-in photomask. The advantage of such a fabrication method is thatthe photo-patterning of subsequent layer does not need to be conductedwith a carefully aligned external photomask. This enables shortening thefabrication time and the use of simpler equipment. The present inventionaddresses the photo-imageable protective polymer that can be used toenhance the contrast of a photo-definable thick film between the regionwhich is directly irradiated and the region shielded by the protectivepolymer film. There is a potential problem related to compatibility ofthe thick film paste with protective layers. This may be addressed byfabricating a protective layer from positive photo-imageable materialswhich do not degrade or dissolve upon contact with the high boilingester-type or ether-type solvents found in the photo-imageable thickfilm pastes, e.g. such solvents include butyl carbitol, butyl carbitolacetate, dibutyl carbitol, dibutyl phthalate, texanol and terpineol. Thecompatibility problem may be resolved by using polymers with pendantacid labile groups which upon either chemical treatment orphoto-irradiation become insoluble to ester-type organic solvents usedwith thick film pastes. These polymer films, however, are highlytransparent to high-pressure mercury lamp ultra violet radiation,typically used in photo fabrication. The mercury lamp radiation includeshigh intensity light at 365 nm (I-line) or 436 nm (g-line) radiation orbroad band unfiltered light including g-line and I-line radiation. TheUV radiation in this wavelength range is frequently called UV-A.

Self-alignment is mostly commonly achieved through back radiation. FIG.1 depicts self-alignment with an UV blocking protective film. In FIG. 1,the substrate (1) is a transparent support material, glass or polymerfilm. The protective layer (2) is coated on the top of the substratematerial and then photo-imaged to have a pattern. A photosensitive thickfilm paste material (3) is applied on top of the photo imaged protectivelayer. After evaporation of the solvent, UV radiation (5) is appliedfrom the backside of the thick film paste, so that photo irradiated areawould be hardened (4). The protective layer can decrease the radiationdose reaching to the photo-definable thick film paste. The degree of UVblocking depends on the thickness and UV absorption of the protectivelayer. The present invention addresses the photo-imageable protectivepolymer that can be used to enhance the contrast of photo-definablethick film between the region which is directly irradiated and theregion irradiated through the protective polymer film.

Preferred UV blocking agents of this invention should meet severalcriteria. First, the blocking agents must absorb UV radiation, and itshould be readily removed with a developing media used for thephotoresistor. It also should have thermal and photochemical stabilityto withstand the fabrication process. Excessive heat could make some ofcompounds to decompose or sublime from the film.

UV blocking agents include aromatic acids which absorbs g-line andI-line radiation. The examples of such acids are nitro benzoic acid,methoxy benzoic acid, nitro naphthalic acid, methoxy naphthalic acid,anthracene sulfonic acid, anthraquinon sulfonic acid, cinnamic acid, and3,5 dimethoxy 4-hydroxy cinnamic acid. Hindered amines are also known toblock UV radiation, and a small amount of aromatic amine can bejudiciously used as a blocking agent as long as the presence of thebasic amine does not neutralize the acid, which catalyzes deprotectionreaction.

Compounds generally known to undergo an excited state intramolecularproton transfer are particularly suitable for this application. Thistype of molecules has an intramolecularly hydrogen-bridged UV absorptionthrough which in the excited singlet state S₁ opens a pathway for thetransformation of ultraviolet radiation into thermal energy. Fundamentalcontributions to charge transfer in the excited state in general and thesubsequent deactivation of excited hydrogen-bonded complexes isresponsible for the dissipation of photo-energy to thermo-energy. Thestructural characteristic of these compounds is a phenolic-type hydroxygroup adjacent to a carbonyl or an aromatic nitrogen proton acceptor, ina position that can form a virtual 6 membered or five memberedtransition state. This compound is not degraded by radiation, so thatits efficiency is higher than one in blocking UV light by converting thephoto-energy to thermal energy repeatedly. However, it has also beenwell established that the chemical characteristic of an additive itselfis not alone the decisive factor for assessing the effectiveness oflight protection. Examples of the compounds which belongs to thiscategory includes 2-(2-hydroxyaryl) benzotriazoles (HBzTs), such as2,4-Bis{[4-(2-ethyl-hexyloxy)-2-hydroxy]-phenyl}-6-(4-methoxyphenyl) -1,3,5-triazine 2-(2-hydroxyphenyl)-4,6-diaryl-1,3,5-triazines (HPTs),such as the 2-hydroxyphenyl-1,3,5-triazines,2-(2′-hydroxyphenyl)-oxazole and -thiazole 3-hydroxyflavones, salicylicacid and it derivatives, such as 5-methoxy and or nitro salicylic acid,o-hydroxynaphthoic acids, benzophenone derivatives, such aso-Hydroxyacetophenone, 2-hydroxy-4-methoxybenzophenone;2-hydroxy-4-methoxy-4′-methylbenzophenone; 1-hydroxy-2-acetonaphthone,7-hydroxyquinoline, 7-hydroxy-1-indanone, 4-hydroxy-3-formylbenzoicacid, 3-hydroxychromone, 2-(2′-hydroxyphenyl) benzazoles, 2-hydroxyanthraquinone, phenolic compounds, such as 2-phenylphenol,o-hydroxystyrene, 2-(2′-cyclohexenyl) phenol,2-(2′-Acetamidophenyl)benzimidazole, 2-acetylindan-1,3-dione.

Additives which can block the UV light by consuming the photoenergythrough irreversible chemical modification can be also used. Cinnamicacid derivatives which absorb UV-A light, under goes [2,2] selfcycloaddition, thus block the UV light.

Migration of UV absorber molecules out of the polymer, particularlysurface blooming by thermal diffusion is serious drawback of thesecompounds, and it is influenced by the free volume of the polymer aswell as by the size and shape of the diffusing molecules. Thus, thecompound has to be selected to have good compatibility with theprotective layer polymer and good solubility in the processing solvent,as well as high blocking efficiency.

Currently, novalac-type of phenolic formaldehyde polymeric materials aretypically used as protective layers in the fabrication process ofelectronic devices utilizing photo-imageable thick film pastes, such asFodel® silver paste commercialized by DuPont, Wilmington Del. The roleof such a protective layer is to maintain spacing between the thick filmdeposit and other substrate structures to prevent contamination of thebottom substrate with the thick film paste. As mentioned above, in somecases, contamination of the bottom substrate may lead to short circuits.The protective layer is then removed by dissolution along with theunimaged thick film material is removed. Novalac-type phenolic polymerabsorbs a sufficient amount of UV light, so that it does block UV lightto a certain extent. Drawback of these protective layers, however, isthat it is frequently found to be damaged during the process of applyingthe paste materials on the top of the protective layer. The cause of thedamage is either the dissolution of the protective layer by solventvapors generated during the paste drying process or plastic deformationof the resist material due to plastization by these vapors. Butylcarbitol, butyl carbitol acetate, dibutyl carbitol, dibutyl phthalate,texanol and terpineol are examples of the solvents currently used inthick film paste formulation.

The present invention uses protective materials that show either lowersolubility or improved compatibility toward high boiling ester-type orether-type solvent vapor so as to reduce the damage of the protectivelayer at same time the protective layer block UV light so that thephotosensitive thick film layer on the top of the protective layer isnot affected by the light irradiated from the backside. New polymers tobe used as a protective layers in electronic device fabrication usingphoto-imageable thick film pastes must be soluble in an organic solventso that the polymer can be applied as a thin film on the top ofprefabricated device layers. Upon either chemical treatment orphoto-irradiation the polymer becomes impervious to ester-type orether-type organic solvents used in the formulation of the thick filmpaste. Since the polymer must undergo a photo-imaging step to be used asthe protective layer, it must be formulated with a photo-responsiveagent. A preferred polymer for this function contains a labile pendantgroup on a side acid functional group, which can be removed from thepolymer pendant group at an appropriate time. One type of pendant acidlabile groups useful in the compositions of this invention can bedescribed by the formulae:

where

-   -   n=0 to 4;    -   R₁ is hydrogen or lower alkyl; R₂ is lower alkyl; and R₃ and R₄        independently are hydrogen or lower alkyl where the definition        of lower alkyl includes alkyl groups having 1 to 6 carbon atoms        and the joining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂        and either R₃ or R₄ may be joined to form a 5-, 6-, or        7-membered ring.

Some examples of acid labile monomeric components that fall within thescope of the invention when used to prepare the polymeric material are:

-   -   1-ethoxyethyl methacrylate (or acrylate),    -   1-butoxyethyl methacrylate (or acrylate),    -   1-ethoxy-1-propyl methacrylate (or acrylate),    -   tetrahydropyranyl methacrylate (or acrylate),    -   tetrahydropyranyl p-vinylbenzoate,    -   1-ethoxy-1-propyl p-vinylbenzoate,        4-(2-tetrahydropyranyloxy)benzyl methacrylate (or acrylate),    -   4-(1-butoxyethoxy)benzyl methacrylate (or acrylate).        This is not meant to be a comprehensive list and the invention        is not limited to these materials.

Another type of pendant acid labile groups useful in the compositions ofthis invention can be described by the formulae:

-   -   R₁ is hydrogen or lower alkyl; R₂ is lower alkyl; and R₃ is        hydrogen or lower alkyl where the definition of lower alkyl        includes alkyl groups having 1 to 6 linear or cyclic carbon        atoms

Some examples of acid labile monomeric components that fall within thescope of the invention when used to prepare the polymeric material are:

-   -   t-butyl methacrylate (or acrylate),    -   Neopentyl methacrylate (or acrylate)    -   1-Bicyclo{2,2,2}octyl methacrylate (or acrylate) and their        derivatives    -   1-Bicyclo{2,2,1}heptyl methacrylate (or acrylate) and their        derivatives    -   1-Bicyclo{2,1,1}hexyl methacrylate (or acrylate) and their        derivatives    -   1-Bicyclo{1,1,1}pentyl methacrylate (or acrylate) and their        derivatives    -   1-adamantyl methacrylate (or acrylate) and their derivatives        This is not meant to be a comprehensive list and the invention        is not limited to these materials.

The preferred molecular weight of these polymers is 7,000-1,000,000. Itis also desirable to use copolymers, either random or block copolymersof monomer units containing those acid labile side groups and some othermonomers which do not have acid labile pendant groups but havehydrophilic groups such as ethylene glycol ethers or carboxylic acidgroups. Molecular weights higher than typical photoresist known in thefield are preferred since the remaining polymer film has to withstandcertain mechanical processes, such as screen printing. Mechanical stressis applied to the film with a rubber squeeze during or after the screenprinting. In order to improve organic solvent resistance, it would bedesirable to have a high amount of acid after the removal of the labilegroups. The amount of monomer in the copolymer suitable forimperviousness to the organic vapor depends on the types of organicsolvent used with the paste. The preferred mole fraction for the monomercontaining labile ester group is 50%, and the more preferred molepercentage is higher than 60%.

Block copolymers can be prepared by well know methods in art, usingmethods typically known as living or controlled polymerization, likeanionic or group transfer polymerization as well as atom transferpolymerization. The terms and techniques regarding living, controlled,and atom transfer polymerization are discussed in “Controlled/LivingRadical Polymerization”, edited by K. Matyjaszewski, Oxford UniversityPress. Random copolymers can be obtained by solution polymerizationusing typical free radical initiator, such as organic peroxide and azoinitiators. Discussion of these polymerization methods can be found in“Polymer Chemistry” Fifth Edition by C. E. Carraher Jr, Marcel DekkerInc., New York, N.Y. (see Chapters 7,8 and 9) or “Polymers” by S. L.Rosen in The Kirk-Othmer Encyclopedia of Chemical Technology, FourthEdition, John Wiley and Sons Inc., New York (see volume 19, pp 899-901).

The photo-initiator is selected from common photo acid generators, suchas aromatic sulfonium phosphofluoride or antimony fluoride, or aromaticiodonium salt with similar anions. The photo acid generators, andexamples of such compounds, are described in a paper by J. V. Crivello,“The Chemistry of Photoacid Generating Compounds” in Polymeric MaterialsScience and Engineering, Vol. 61, American Chemical Society Meeting,Miami, Fla., Sep. 11-15, 1989, pp. 62-66 and references therein. Theselected photo acid generator should not undergo decomposition ordissolution during the development stage. Nonionic photoacid generator,such as PI-105 (Midori Kagaku Co, Tokyo, Japan) or high moleuclar weightphoto acid generator, such as Cyracure UVI 6976 (Dow, Midland, Mich.),CD-1012 (Aldrich Chemical, Milwaukee, Wis.) are examples of such photoacid generator.

The UV blocking agent is selected to have compatibility with all theseadditives, and should be soluble in the solvent. In addition, it shouldnot decompose or be washed out during the radiation and developmentstages. The preferred UV blocking agents include 2-(2-hydroxyphenyl)benzotriazoles, 2,2′-dihydroxy-benzophenone; 3,5 dimethoxy 4-hydroxycinnamic acid. The amount of UV blocking agent can be adjusted dependingon the degree of UV blocking required. The amount of additionalradiation required to generate a residue -free pattern with addition ofa corresponding amount of UV blocking agent is a good indication howeffectively blocking agent blocks light. The absolute value can changedepending on the thickness of film and radiation source. The efficacy ofthe UV blocking agent depends on the absoprtivity, energy dissipationmechanism as well as presence of impurities. Using a high pressuremercury lamp, one percent of 2-(2-hydroxyphenyl)benzotriazoles mayrequire 3 J/cm² more and 3,5 dimethoxy 4-hydroxy cinnamic acid mayrequire about 900 mJ/cm² more energy to have 98% confidence that theresidue-free patterning would be photolytically created.

Carbon nanotubes (CNT) have been show to have strong UV absorption asdescribed by Chen et al for single-walled CNT (SWNT) (Science,282:95-98, 1998) and by Jin et al for multi-walled CNT (MWNT) (ChemicalPhysics Letters, 318:505-510, 2000). In one embodiment, carbon nanotubescan be selected as a sole UV blocking agent. In another embodiment,carbon nanotubes can be used together with other agent as an additionalUV blocking agent. In yet another embodiment, a mixture of SWNT and MWNTcan be used as a sole or an additional UV blocking agent.

To fabricate a device using the present invention, a 0.5 to 5 micronthick polymer coating of polymers with pendant labile acid groups andphoto-active reagents is applied to a substrate. Such coatings could beachieved by spin coating or table coating using a blade in anappropriate organic solvent. The preferred organic solvents for applyingthe coating are propylene glycol 1-monomethyl ether 2-acetate (PGMEA) orcyclohexanone. Next, the solvent is removed by heating the substrate tobetween 70 to 100° C. for typically 1 to 3 minutes on a hot plate. Thecoating is now ready to be patterned by UV photo-irradiation. UVirradiation followed by heat treatment will cleave acid labile pendantgroup to convert the ester to the acid. The UV photoirradiation sourcemay use 193 nm laser radiation or a mercury lamp. For the higherwavelength than 248 nm may require addition of a small amount (10-10000ppm) of photosensitizer which increases the absorption of UV light. Theexamples of photosensitizer include, but not limited toisopropylthioxanthone (ITX), 2,4-Diethyl-9H-thioxanthen-9-one (DETX),benzophenone. UV irradiation dose is 50 to 3000 mJ/square centimeter.Post exposed baking conditions are typically 120 to 140° C. for 1 to 3minutes. This treatment causes the exposed area being soluble in anaqueous base developing solvent. The basic developing solvents mayinclude a carbonate solution or a low concentration sodium or potassiumhydroxide solution. Preferably, commercial aqueous base developer, suchas AZ 300, 400 or 500, obtained from Clariant Corporation, AZ ElectronicMaterials Somerville, N.J. 08876-1258, can be used. After development, apatterned template is formed. The remaining protective film is stillsoluble in organic solvents, thus its protective function toward thethick film paste is limited. The film can be converted to a filmcontaining a high level of polycarboxylic acid which is insoluble in thecommon organic solvents employed in thick film pastes by exposure to UVlight and subsequent heat treatment. The UV irradiation dose is 50 to4000 mJ/square centimeter. Post exposed baking conditions are typically120 to 140 C for 1 to 3 minutes.

The amount of UV blocking agent to the final polymer ranges between 0.1to 20% by weight depending on the agents as a mixture with the polymerof the protective layer. The amount of the agent required for theapplication depends on the types of UV light, the thickness of theprotective film and the abortion characteristics of the agent. Some ofthe agent could be sublimed during the heat treatment, and may undergophotolytic or thermal decomposition, so that the efficacy of UV blockingcould be process dependent. Too much blocking agent will make thephotoresist less sensitive, and may require a large amount of photoenergy for photodevelopment. The amount of photoblocking agent can bemodulated to be optimum condition for photodefinition and photoblocking.

The negatively imageable thick film paste of interest is aqueous basedevelopable paste, such as Fodel silver paste commercialized by DuPont,Wilmington Del. It also includes such paste containing carbon nanotubesfor field emission display applications. Thick film paste is applied onthe top of the converted protective layer by such methods as screenprinting, filling the vacancies in the patterned template generated byphoto development. Subsequently, the thick film paste is photoirradiated from the back side of the structure. The paste located in thepatterned template where the protective film is removed by photo-imagingwould be imaged preferentially. The paste is negatively developed uponirradiation, so that the paste becomes insoluble to developing solvents.Typically, these thick film pastes are developed by gentle spray of anaqueous base solution. The unimaged paste is washed out within certaintime which is called the time-to-clear (TCC). Typically, the spray willlast 1.5 to 3.0 times the TTC. The irradiated protective layer issoluble in the aqueous base solution so that it is removed while theunimaged thick film paste is being removed as it is spray developed.

EXAMPLES Examples 1-9

3.590 grams of poly(ethoxytriethylene glycol methacrylate-b-t-butylmethacrylate), (with a degree of polymerization, D.P., of 37/100 and anumber average molecular weight, Mn, of 10,000), 0.890 grams ofhomopolymer of t-butyl methacryllate (with D. P. equal to 5), 1.586grams Cyracure® UVI-6976 solution (Dow Chemical), and 0.131 grams of a2% Quanticure ITX (Aldrich) solution in Propylene glycol monomethylether acetate (PGMEA), 0.131 g of a 2% of2,3-Diazabicyclo[3.2.2]non-2-ene, 1,4,4-trimethyl-, 2,3-dioxide (TAOBN)solution in PGMEA, and various amounts of a 1% solution of 2-hydroxy4-methoxy benzophenone (0.06 g for example 1) in PGMEA were mixed with8.328 g of PGMEA to give a clear solution.

Optionally, carbon nanotubes can be added to the solution to a finalconcentration between 0.1-20%. Sonication can be performed to dispersecarbon nanotubes.

Using a 0.5 mil doctor blade, the solution was cast on an ITO-coatedglass plate and allowed to air dry for 10 minutes. The film was thendried for 2 min at 70 degrees C. hot plate. The film was exposed with300-3000 mJ/cm2 broad band UV light using a 20 micron photomask and thenheat treated on a hot plate at 120 degrees C. for 2 min. The imaged partwas developed by dipping into a 0.5% sodium carbonate solution. Thephotosensitivity as estimated from visual inspection of the image of thepattern in the photomask is given in Table 1. TABLE 1 Weight % of2-hydroxy-4-methoxy Photo patterning benzophenone with 600 mJ/cm2 0.1Good image 0.2 Good image 0.5 Good image 1.0 Good image 2.0 Good image4.0 Latent image 8.0 Latent image 16 No image 20 No image

Examples 10-13

3.273 grams of poly(ethoxytriethylene glycol methacrylate-b-t-butylmethacrylate), (D.P. 37/100, Mn 10,000), 0.327 grams of (D.P.=5)homopolymer of t-butyl methacryllate, 0.785 grams Cyracure® UVI-6976solution (Dow Chemical), and 0.17 grams of a 1% Quanticure ITX (Aldrich)solution in PGMEA, 0.681 g of a 1% TAOBN solution in PGMEA, and variousamount of 2-(2-Hydroxy-5-Methylphenyl) Benzotriazole (0.0225 g forexample 10) were mixed in 4.74 g of PGMEA to a clear solution.

Optionally, carbon nanotubes can be added to the solution to a finalconcentration between 0.1-20%. Sonication can be performed to dispersecarbon nanotubes.

Using a 0.5 mil doctor blade, the solution was cast on an ITO coatedglass plate and allowed to air dry for 10 minutes. The film was thendried for 2 min at 70 degrees C. hot plate. The film was exposed with300-3000 mJ/cm2 broad band UV light using a 20 micron photomask, thenheat treated on a hot plate at 140 degrees C. for 2 min. The imaged partwas developed by dipping into a 0.5% sodium carbonate solution. Table 2lists the amount of radiation required to make a clean image of thepattern in the photomask as determined by visual inspection. TABLE 2Weight % of 2-(2-Hydroxy-5- Amount of radiation (mJ/cm2) neededMethylphenyl) Benzotriazole to make a clean image 0.5 600 1.0 1200 2.02400 4.0 3000

Examples 14-16

3.273 grams of poly(ethoxytriethylene glycol methacrylate-b-t-butylmethacrylate), (D.P. 37/100, Mn 10,000), 0.327 grams of DP=5 homopolymerof t-butyl methacryllate, 0.785 grams Cyracure® UVI-6976 solution (DowChemical), and 0.17 grams of a 1% Quanticure ITX (Aldrich) solution inPGMEA, 0.681 g of a 1% TAOBN solution in PGMEA, and various amount of3,5-dimethoxy-4-hydroxy-cinnamic acid (0.045 g for example 14) weremixed in 4.74 g of PGMEA to a clear solution.

Optionally, carbon nanotubes can be added to the solution to a finalconcentration between 0.1-20%. Sonication can be performed to dispersecarbon nanotubes.

Using a 0.5 mil doctor blade, the solution was cast on an ITO coatedglass plate and allowed to air dry for 10 minutes. The film was thendried for 2 min at 70 degrees C. hot plate. The film was exposed with600-3000 mJ/cm2 broad band UV light using a 20 micron photomask, thenheat treated on a hot plate at 140 degrees C. for 2 min. The imaged partwas developed by dipping into a 0.5% sodium carbonate solution. Table 3lists the amount of radiation required to make a clean image of thepattern in the photomask as determined by visual inspection. TABLE 3Weight % of 2-(2-Hydroxy-5- Amount of radiation (mJ/cm2) neededMethylphenyl) Benzotriazole to make a clean image 1.0 1200 2.0 1800 3.01800

1. A composition comprising: a) a UV blocking agent selected from thegroup consisting of: nitro benzoic acid, methoxy benzoic acid, nitronaphthalic acid, methoxy naphthalic acid, 3,5 dimethoxy,4-hydroxycinnamic acid, cinnamic acid and their derivatives, 2 hydroxyl arylbenzotriazole and its derivatives, 2 hydroxy benzophenone and itsderivatives, anthracene sulfonic acid and its derivatives, and carbonnanotubes and b) a polymer in which at least 50 mole percent of themonomers in the polymer comprise a structure selected from the groupconsisting of:

 where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ ishydrogen or a lower alkyl where the definition of lower alkyl includesalkyl groups having 1 to 6 linear or cyclic carbon atoms;

 where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ andR₄ are independently hydrogen or a lower alkyl where the definition oflower alkyl includes alkyl groups having 1 to 6 carbon atoms and thejoining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂ and either R₃ orR₄ to form a 5-, 6-, or 7-membered ring; and

 where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ andR₄ are independently hydrogen or a lower alkyl where the definition oflower alkyl includes alkyl groups having 1 to 6 carbon atoms and thejoining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂ and either R₃ orR₄ to form a 5-, 6-, or 7-membered ring.
 2. The composition of claim 1wherein the polymer is selected from the group consisting of1-ethoxyethyl methacrylate, 1-ethoxyethyl acrylate, 1-butoxyethylmethacrylate, 1-butoxyethyl acrylate, 1-ethoxy-1-propyl methacrylate,1-ethoxy-1-propyl acrylate, tetrahydropyranyl methacrylate,tetrahydropyranyl acrylate, tetrahydropyranyl p-vinylbenzoate,1-ethoxy-1-propyl p-vinylbenzoate, 4-(2-tetrahydropyranyloxy) benzylmethacrylate, 4-(2-tetrahydropyranyloxy) benzyl acrylate,4-(1-butoxyethoxy) benzyl methacrylate,, 4-(1-butoxyethoxy) benzylacrylate t-butyl methacrylate, t-butyl acrylate, neopentyl methacrylate,neopentyl acrylate, 1-Bicyclo{2,2,2}octyl methacrylate (or acrylate) andtheir derivatives, 1-Bicyclo{2,2,1}heptyl methacrylate (or acrylate) andtheir derivatives, 1-Bicyclo{2,1,1}hexyl methacrylate (or acrylate) andtheir derivatives, 1-Bicyclo{1,1,1}pentyl methacrylate (or acrylate) andtheir derivatives and 1-adamantyl methacrylate (or acrylate) and theirderivatives.
 3. The composition of claim 1 wherein the UV blocking agentcomprises more than one members selected from the group consisting of:nitro benzoic acid, methoxy benzoic acid, nitro naphthalic acid, methoxynaphthalic acid, 3,5 dimethoxy,4-hydroxy cinnamic acid, cinnamic acidand their derivatives, 2 hydroxyl aryl benzotriazole and itsderivatives, 2 hydroxy benzophenone and its derivatives, anthracenesulfonic acid and its derivatives, and carbon nanotubes.
 4. A processcomprising: a) coating an electronic device structure with a positivephoto-imageable protective layer comprising a UV blocking agent selectedfrom the group consisting of: nitro benzoic acid, methoxy benzoic acid,nitro naphthalic acid, methoxy naphthalic acid, 3,5 dimethoxy,4-hydroxycinnamic acid, cinnamic acid and their derivatives, 2 hydroxyl arylbenzotriazole and its derivatives, 2 hydroxy benzophenone and itsderivatives, and anthracene sulfonic acid and its derivatives and carbonnanotubes and a polymer in which at least 50 mole percent of themonomers in the polymer comprise a structure selected from the groupconsisting of:

 where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ ishydrogen or a lower alkyl where the definition of lower alkyl includesalkyl groups having 1 to 6 linear or cyclic carbon atoms;

 where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ andR₄ are independently hydrogen or a lower alkyl where the definition oflower alkyl includes alkyl groups having 1 to 6 carbon atoms and thejoining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂ and either R₃ orR₄ to form a 5-, 6-, or 7-membered ring; and

 where R₁ is hydrogen or lower alkyl; R ₂ is a lower alkyl; and R ₃ andR₄ are independently hydrogen or a lower alkyl where the definition oflower alkyl includes alkyl groups having 1 to 6 carbon atoms and thejoining of R₁ and R₂, or R₁ and either R₃ or R₄, or R₂ and either R₃ orR₄ to form a 5-, 6-, or 7-membered ring.
 5. The process of claim 4wherein the polymer is selected from the group consisting of:1-ethoxyethyl methacrylate, 1-ethoxyethyl acrylate, 1-butoxyethylmethacrylate, 1-butoxyethyl acrylate, 1-ethoxy-1-propyl methacrylate,1-ethoxy-1-propyl acrylate, tetrahydropyranyl methacrylate,tetrahydropyranyl acrylate, tetrahydropyranyl p-vinylbenzoate,1-ethoxy-1-propyl p-vinylbenzoate, 4-(2-tetrahydropyranyloxy) benzylmethacrylate, 4-(2-tetrahydropyranyloxy) benzyl acrylate,4-(1-butoxyethoxy) benzyl methacrylate, 4-(1-butoxyethoxy)benzylacrylate t-butyl methacrylate, t-butyl acrylate, neopentyl methacrylate,neopentyl acrylate, 1-Bicyclo {2,2,2}octyl methacrylate (or acrylate)and their derivatives, 1-Bicyclo {2,2,1}heptyl methacrylate (oracrylate) and their derivatives, 1-Bicyclo {2,1,1}hexyl methacrylate (oracrylate) and their derivatives, 1-Bicyclo {1,1,1}pentyl methacrylate(or acrylate) and their derivatives and 1-adamantyl methacrylate (oracrylate) and their derivatives.
 6. The process of claim 4 wherein theUV blocking agent comprises more than one members selected from thegroup consisting of: nitro benzoic acid, methoxy benzoic acid, nitronaphthalic acid, methoxy naphthalic acid, 3,5 dimethoxy, 4-hydroxycinnamic acid, cinnamic acid and their derivatives, 2 hydroxyl arylbenzotriazole and its derivatives, 2 hydroxy benzophenone and itsderivatives, anthracene sulfonic acid and its derivatives, and carbonnanotubes.
 7. An electronic device fabricated by the process of claims4, 5 or 6.